Burner for light combustible materials

ABSTRACT

A method and two embodiments of apparatus for providing efficient combustion wherein air and combustible materials are introduced into a bottom portion of a vertical chamber which is substantially open at its top, the combustible material being dispersed upwardly through a combustion zone with combustion products exiting through the open top of the chamber, gases which tend to be trapped beneath the combustion zone being vented from the chamber through suitable conduits and returned to an upper portion of the chamber if desired for more complete combustion. One embodiment of the apparatus includes a feed duct extending downwardly through the chamber for introducing combustible material thereinto. Another embodiment of the apparatus includes a feed assembly with a hopper and feed mechanism for respectively receiving combustible material and urging it upwardly through a feed duct into the chamber.

Gardner United States Patent 1 BURNER FOR LIGHT COMBUSTIBLE MATERIALS v5 i [76] Inventor: OrianR.Gardner,4l9;Marin I Avenue Mill valley Calif.9494i [22] Filed: July19, 1971 Appl. Nil-$163,869

{5 21, u. s. c|. .-.....;..Q 110/18 R, lie/22110736.; [5 1] Int. Cl. .QF23g 7/00 [58] Field of Search..... [10/7 A, 12, 18 R,- v ll0/2-9, 36,45

{56] References Cited I l v UNITED STATES PATENTS 2,140,522 12/1938;Foresman 1 10/36' 2,153,106 =4/l939 Taylor ll0/29X 2,252,326 8/194! mLewers, 110/12 2,702,013 2/1955 Atteberry....'... 1'10/45 x 1 2,653,5549/1953 Hatton et a]... 110/29 Kocee .Q .L....ll0/l8 H 1. July 0, 7

I Primary fxaminer Kennethw. Sprague Attorney-Charles M. Fryeret al. I

Y A method and two embodiments of apparatus for providing efficientcombustion wherein airiand combusti- "ble materials are introduced intoabottomportion of a vertical cha'mb'erwhieh is substantiallyopen atitstop, the combustible material being dispersed upwardly through'acombustion zone with combustion products exiting through the open top ofthe chamber, gases which tendto betrapped beneath the combustionzonebeing vented from the chamber through suitable conduits andretumed to anupper portion of the chamber if desired for more complete combustion.One embodimm of the apparatus includes'a feed duct extending downwardlythrough the chamber for introduein gtcombustible' material thereinto.-Another 'embodiment of the apparatus ineludesa feed assembly withahopper and feed mechanism forrespectiv'ely receiving combustible'material and urging it upwardly through a feed duct intothechamber.

.. ll Claims, 2

PATENIEU JUL 0 I975 INVENTOR.

ORIAN R. GARDNER FIG....2

BURNER FOR LIGHT COMBUSTIBLE MATERIALS RELATED U.S. PATENTS U.S. Pat.application Ser. No. 821,897, entitled Rice Hull Burners" and filed onMay 5, 1969 by Orian R. Gardner, now U.S. Pat. No. 3,626,876, issued onDec. 14, 197i.

The present invention relates to combustion apparatus and methodsparticularly adapted for the'burning of light combustible materials suchas rice hulls and straw from various grains for example. Various devicesand methods are known in the prior art for these purposes. However,there remains a need for improvements to meet various requirements forcombustion apparatus and processes. One such general requirement is theprovision of efficient and economical means for burning such materials.There are often substantial quantities of such materials which can beprocessed or disposed of only by burning. In many cases, combustionproducts from these materials does not provide an economic return.Accordingly, it is desirable that capital and operating costs for thecombustion process be minimal.

In the processing of other materials such as rice hulls for example, theash or combustion product may be usable and thus permit an economicreturn. However, the need for efficiency and economy remains. Inaddition for combustible materials of this type, it is necessary toprovide for accurate control or regulation of the combustion process inorder to provide various desired 1 region and the degree or rate ofcombustion which may .be uniformly maintained to regulate both thequality and quantity of combustion products, either solids or gases,which are introduced into the atmosphere.

The reference cited above provides a burner which overcomes many of theproblems and tends to meet the various requirements set forth above. Theburner described in that reference is of relatively simple constructionincluding a vertical chamber with combusti bles and air being introducedin a bottom portion of the chamber and pass upwardly through acombustion region while combustion products pass out of the chamberthrough an opening at the top. Such a design has been found to permitgood control over the combustion process.

However, under certain conditions such as when combustible materialhaving a high moisture content is being burned for example, thecombustion process may tend to' be disrupted by steam becoming trappedbeneath solid material suspended in the chamber during combustion. Whenpressure of the steam is sufficiently high, it erupts upwardly throughthe suspended solids and tends to interfere with the otherwise uniformcombustion characteristics.

desired for more complete burning of any combustible materials therein.

Lighters may also be used in conjunction with the chamber to introducecombustion supporting fluids or material such as fuel, for example, tomaintain high temperatures in the combustion zone and to establish ormaintain desired combustion characteristics.

It is also an object of the present invention to provide a burner of thegeneral type described above being particularly adapted to the burningof relatively light combustible materials such as straw which may besomewhat difficult to handle because of its bulkiness. In one embodimentof the invention for example, a feeder assembly includes hopper meansfor receiving combustible material and a feed mechanism for urging thematerial through a feed duct into the chamber. With the feed ductpenetrating the bottom of the chamber, the entire chamber interior isalso available to form the combustion zone. This feature is ofparticular advantage for bulky materials since material maybe burned ata greater rate. The gas vent and/or lighter arrangements may also beused to advantage in this embodiment for example when straw or othermaterial having a relatively high moisture content is being burned.

Other advantages and objects of the present invention are believedapparent in the following description of method and apparatusembodiments of the present invention which are also illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view in elevation ofa burner constructed according to the present invention and suitable forpracticing the method of the present invention; and

FIG. 2 is a similar view of another embodiment of a burner constructedaccording to the present invention.

A preferred embodiment of the present invention as illustrated in FIG. 1may be adapted for the combustion of various materials, particularlyrelatively light combustible materials such as rice hulls and straw forexample, which can be suspended or carried upwardly through a combustionzone by air and/or convection current.

Referring now to FIG. 1, a housing 11 forms a generally verticalcombustion chamber 12 which is open at its top. A concentricallyarranged feed duct 13 opens into a bottom portion of the chamber and issupported by tie-rods 14. The bottom portion 15 of the feed duct tapersinwardly toward an opening 16. The topportion 17 of the cylindrical feedduct flares outwardly to form a hopper for receiving combustiblematerial which pass downwardly through the duct into the chamber 12. Thefeed duct of this embodiment is particularly adapted for use withrelatively free-flowing combustible materials. However, additional meansmay be employed for urging combustibles through the duct if necessary ina manner somewhat like that described below with reference to theembodiment of FIG. 2, for example. The

size of the feed duct with respect to the housing 11 may be selected tooptimize the feed rate with respect to the rate of combustion in thechamber for various materials.

Air for supporting combustion in the chamber is introduced at the baseof the chamber through inlet ports I 18. Air flow through the ports 18may be induced by convection currents in the chamber once combustioncommences or it may be forced therethrough by 'a conventional manifoldand blower of the type described and illustrated in the reference notedabove, for example.

Agitator means 19 are arranged in the bottom of the chamber 12 fordispersing combustible material passing downwardly out of the feed duct13. The agitator also assists in intermixing the combustibles with airfrom the ports 18 and urging it upwardly in the chamber toward acombustion zone discussed in greater detail below. The agitator means asillustrated in FIG. 1, is a bladed element secured to a shaft 21 whichrotatably penetrates the floor 22 of the chamber 12 and is driven by amotor 23 through suitable reduction gearing 24. The reduction gearing'may include conventional variable means (not shown) for adjusting thespeed of rotation for the agitator.

For handling combustible materials which tend to be cohesive, such asstraw for example, breaker means 26 are arranged between the agitatorand the opening 16 of the feed duct. The breaker means as illustrated inFIG. 1, comprises a curved rod which is also mounted on the shaft 21 forrotation with the agitator 19. This rod structure serves to initiallyscatter combustible material exiting the feed duct so that it may bemore readily dispersed by the agitator.

When the combustion apparatus of the present invention is employed forburning certain materials such as combustibles having a relatively highmoisture content, additional means are contemplated for providinguniform and controllable combustion conditions in the chamber. Prior todescribing these means it is noted that in operation of the presentdevice, combustibles are dispersed by the agitator and carried upwardlythrough the chamber 12 either by air flow or by convection currentsafter the material is ignited and combustion is commenced. Duringcombustion, the material tends to be suspended in acombustion zone,generally indicated at 27, which is formed along the vertical chamber12. After combustion of succeeding portions of the material is complete,the degree of combustion depending on the particularly type of materialbeing burned, its feed rate, temperature in the chamber and the rate ofair flow which are selected for example, solid and gaseous combustionproducts are carried upwardly and out of the open top of the chamberaround the feed duct portion 17.

Since substantial quantities of materials may be suspended in thechamber during combustion and since the combustible material is fedupwardly into the combustion chamber, gases such as steam may becometrapped below or in a lower portion of the combustion zone 27. Whenpressure of the trapped gas rises sufficiently, it tends to eruptupwardly through the suspended combustible material. When this occurs,the uniform rate of combustion proceeding in the zone 27 is disrupted.Part of the combustible materials in the zone 27 may also be carriedupwardly and out of the chamber 12 by the erupting gas before it hasbeen oxidized to the degree desired.

To overcome this problem, vent means such as orifices 28 illustrated inthe embodiment of FIG. 1 are arranged below a substantial portion of thecombustion zone-27 for releasing the trapped gases from the chamexample.

The arrangement of tubes 29 also facilitates better pollution controlfor the device since the upper ends 31 of the tubes open into thechamber at least above a substantial portion of the combustion zone 27.Thus, the vented gasesare reintroduced into the chamber to permit morecomplete oxidation of any combustible material remaining therein. Aswill be more apparent from the following description with reference tothe embodiment of FIG. 2, the orifices 28 may also be simply formed inthe housing itself so that the gases are merely vented to theatmosphere, for example, when no combustibles are present in the gas.

Certain operating conditions, such as during the burning of materialswith high moisture contents, may tend to undesirably reduce thetemperature in the combustion zone. To overcome this problem, lightermeans such as the tubes 32 are contemplated around the chamber forintroducing combustion supporting material or fluid, such as variouspetroleum products or even additional air for example, into the chamberadjacent the combustion zone 27 Such material may be delivered into thetubes 32 for introduction into the chamber from a suitable source or airmay be simply allowed to flow into the chamber under the influence ofconvection currents in the chamber. Regardless of the material to beintroduced into the chamber through the tubes, some control means suchas a control valve (not shown) may be desired to either close the tubesor regulate the flow of material therethrough to further vary combustionpropertiesin the chamber.

Another embodiment of the invention, having reference now to FIG. 2,includes a combustion device which is generally similar to that ofFIG. 1. Accordingly, features of the embodiment in FIG. 2 are indicatedby similar primed numerals.

The chamber 12 of FIG. 2 is generally similar to the chamber 12 ofFIG. 1. However, the feed duct 13', while delivering material into thebase of the chamber like the duct 13 of FIG. 1, is arranged outside thechamber and penetrates its floor 22'. Thus, the entire chamber interioris open and available to form the combustion zone therealong. The extentof the zone along either of the vertical chambers 12' or 12 of coursedepends on the type of material being burned and other parametersas'discussed above.

This open feature of the chamber 12' makes it particularly useful forburning material such as straw for example, the effective volume ofwhich is rapidly reduced during combustion. The material may beintroduced at a faster rate into the entirely open chamber.

Similar vent means are employed as in the embodiment of FIG. 1. However,the tubes 29 are externally arranged about the housing with their lowerand upper openings 28' and 31' being formed in the housing or wall 11'.

In the embodiment of FIG. 2, the feed duct 13 is part of a feederassembly 51. The feeder assembly includes a hopper 52 having a downspoutor throat 53 intersecting the feed duct 13'. A feed mechanism 54 includes reciprocable elements 56 and 57 pivotally coupled for operationby a single flywheel 58 which may be driven for example by a motor (notshown). Combustible material placed in the hopper is urged or packedinto the feed duct 13 by the element 56 while the element 57 urgesmaterial through the duct 13' into the chamber.

Such an arrangement is particularly suited for materials such as strawwhich are difficult to handle and which may be desirable if somewhatcompressed before entering the chamber.

The agitator 19' is particularly suited for use with such materials andfunctions to replace both the agitator l9 and breaker means 26 of FIG.1.

Various features or steps are described above for a method of operationcontemplated for the present invention and adaptable to the embodimentof either FIG. 1 or FIG.'2. However, to summarize such operation,combustiblematerial is introduced into the chamber 12 or 12 near itsbase through the feed duct 13 or 13'. air is also introduced through themeans 18 or 18. During combustion, the material is dispersed by theagitator 19 or 19" and carried upwardly into the combustion zone by airflow or convection currents with the material tending to remainsuspended in the combustion zone until combustion is complete to adesired degree. Combustion products, both solid and gaseous, passupwardly from the combustion zone and out the opentop of the chamber.

The vent means and lighter means may be selectively employed, eitheralternatively or in combination, to further enhance desired combustioncharacteristics in the chamber. As discussed above, gases trapped belowthe combustion zone may be vented out of the chamber and reintroducedinto the chamber above the combustion zone if desired or necessary. Thelighter means may be employed as desired to maintain combustion in thezone 27 or 27'.

Material exiting the chamber may be further treated or cured,particularly if a usable product is to be obtained for example from theburning of rice bulls. The curing may comprise storing the combustionproduct in a substantial mass so that it is further affected by residualheat as discussed in the reference noted above. It

may also comprise rapid cooling of the combustion a vertically arrangedcombustion chamber formed by an outer cylindrical wall and having anopening at its top means for delivering combustible material and airinto a-bottom portion of the chamber means for urging the combustiblematerial upwardly into and through the combustion chamber withcombustion of the material occurring as it moves upwardly through andtends to be suspended within a combustion zone formed generally midwayalong the vertical'chamber with combustion products exiting the chamberthrough its open top, and vent means in communication with the chamberinterior substantially below the combustion zone for releasing gasestending to be trapped in the chamber by combustible material suspendedin the combustion zone. 2. The apparatus of claim 1 wherein the ventmeans is also in communication with the chamber interior substantiallyabove the suspended combustible material in the combustion zone forreintroducing vented gases into the chamber and permitting oxidation ofany combustible portion of the vented gases.

3. The apparatus of claim 2 wherein the vent means comprises a pluralityof tubes vertically arranged about the inside periphery of the chamberadjacent the combustion zone.

4. The apparatus of claim 1 further comprising a cylindrical feed ductvertically arranged in said chamber and having an opening adjacent thebase of said chamber for delivering combustible material thereto, saidmeans for urging combustible material upwardly into the chambercomprising an agitator means at the base of said chamber for receivingcombustible material from the feed duct and dispersing it withcombustion of the material taking place as it moves upwardly through acombustion zone formed midway along the vertical chamber between thefeed duct and the outer cylindrical wall of the chamber.

5. The apparatus of claim 4 further comprising lighter means incommunication with the chamber interior generally adjacent thecombustion zone for the introduction of combustion supporting material.

6. The apparatus of claim 4 further comprising rotatable breaker meanshaving relatively thin radially projecting elements arranged between thebase opening in the feed duct and the agitator for initially scatteringcombustible material from the feed duct and facilitating itsdispersement by the agitator.

7. The apparatus of claim 6 wherein the agitator and breaker means arearranged on a common rotatable shaft penetrating a floor member of thechamber.

8. The apparatus of claim 1 further comprising lighter means incommunication with the chamber interior generally adjacent thecombustion zone for introducing combustion supporting fluids thereinto.

9. In a method of burning relatively light combustible material in agenerally vertically arrangedv chamber which is substantially open atits top, the steps comprising introducing combustible material and airin a base portion of the chamber with agitation for intermixing thecombustible material with air,

igniting the combustible material,

urging the material upwardly through the chamber with combustion of thematerial taking place in a combustion zone formed generally midway alongthe vertical chamber while combustion products move upwardly from thecombustion zone,

removing the combustion products from the chamber through its open top,and

venting an interior portion of the chamber below a substantial portionof the combustion zone and thereby releasing from the chamber gasestending to be trapped in the chamber beneath the combustion zone andpreventing disruption of the combustion zone.

10. The method of claim 9 further comprising the steps of receiving thegases vented from the chamber chamber beneath the combustion zoneinclude steam.

1. Apparatus for burning light combustible materials, comprisingavertically arranged combustion chamber formed by an outer cylindricalwall and having an opening at its top means for delivering combustiblematerial and air into a bottom portion of the chamber means for urgingthe combustible material upwardly into and through the combustionchamber with combustion of the material occurring as it moves upwardlythrough and tends to be suspended within a combustion zone formedgenerally midway along the vertical chamber with combustion productsexiting the chamber through its open top, and vent means incommunication with the chamber interior substantially below thecombustion zone for releasing gases tending to be trapped in the chamberby combustible material suspended in the combustion zone.
 2. Theapparatus of claim 1 wherein the vent means is also in communicationwith the chamber interior substantially above the suspended combustiblematerial in the combustion zone for reintroducing vented gases into thechamber and permitting oxidation of any combustible portion of thevented gases.
 3. The apparatus of claim 2 wherein the vent meanscomprises a plurality of tubes vertically arranged about the insideperiphery of the chamber adjacent the combustion zone.
 4. The apparatusof claim 1 further comprising a cylindrical feed duct verticallyarranged in said chamber and having an opening adjacent the base of saidchamber for delivering combustible material thereto, said means forurging combustible material upwardly into the chamber comprising anagitator means at the base of said chamber for receiving combustiblematerial from the feed duct and dispersing it with combustion of thematerial taking place as it moves upwardly through a combustion zoneformed midway along the vertical chamber between the feed duct and theouter cylindrical wall of the chamber.
 5. The apparatus of claim 4further comprising lighter means in communication with the chamberinterior generally adjacent the combustion zone for the introduction ofcombustion supportinG material.
 6. The apparatus of claim 4 furthercomprising rotatable breaker means having relatively thin radiallyprojecting elements arranged between the base opening in the feed ductand the agitator for initially scattering combustible material from thefeed duct and facilitating its dispersement by the agitator.
 7. Theapparatus of claim 6 wherein the agitator and breaker means are arrangedon a common rotatable shaft penetrating a floor member of the chamber.8. The apparatus of claim 1 further comprising lighter means incommunication with the chamber interior generally adjacent thecombustion zone for introducing combustion supporting fluids thereinto.9. In a method of burning relatively light combustible material in agenerally vertically arranged chamber which is substantially open at itstop, the steps comprising introducing combustible material and air in abase portion of the chamber with agitation for intermixing thecombustible material with air, igniting the combustible material, urgingthe material upwardly through the chamber with combustion of thematerial taking place in a combustion zone formed generally midway alongthe vertical chamber while combustion products move upwardly from thecombustion zone, removing the combustion products from the chamberthrough its open top, and venting an interior portion of the chamberbelow a substantial portion of the combustion zone and thereby releasingfrom the chamber gases tending to be trapped in the chamber beneath thecombustion zone and preventing disruption of the combustion zone. 10.The method of claim 9 further comprising the steps of receiving thegases vented from the chamber and reintroducing them into the chamberabove a substantial portion of the combustion zone to provide foroxidation of any combustible portion of the vented gases.
 11. The methodof claim 9 wherein the combustible materials introduced into the chamberhave a substantial moisture content and the gases vented from thechamber beneath the combustion zone include steam.